NSV 19431 and YY Centauri—Two Mira Variables

摘要

Visual observations of NSV 19431 and YY Cen spanning the twentyeight years 1980 through 2007 are discussed. These show NSV 19431 is a Mira star of mean period of 298.1 days and visual brightness range of 10.8 to fainter than 15.0. Elements for determining the dates of maximum brightness are JD 2447700 + 298.1 days (+10 days). The O–C diagram shows what appear to be random cycle-to-cycle fluctuations with a current mean cycle of 298.1 days, evident from the maximum of JD 2447700 (1989).